article: Tom was a farmer. He worked on the farm all day,but sometimes he went to the town market to sell fruit and vegetables. One day, a terrible sound attracted his attention in the town market. He saw a young bull for sale. The bull was white and yellow. It was looking at Tom in fear. Tom walked up and touched its head gently. Just at that time they both seemed to have known each other for a long time. How amazing!Tom bought it at once and called it Amba.
  From then on , Tom and Amba got on well with each other. But some friends told him that it was dangerous to have such a close relationship with an animal.
  One afternoon , Tom was walking through the forest with Amba. Suddenly , Amba stopped walking and kept pushing Tom with its head. Tom was very surprised and looked around. There was a big snake in front of him. It was beautiful but poisonous. Quickly Amba stepped on the snake's tail with its foot and at the same time Tom picked up a stick and hit the snake's head heavily. Soon the snake . died.
  Tom was very grateful for Amba's help. When people heard this, they were shocked at the bull's expression of love for Tom. But for Tom, Amba was not a bull but a member of his family.
question: The passage mainly wants to tell us  _  .
options: the love between humans and animals the fight between a bull and a snake how to keep an animal how to train an animal